<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
  .box{
    width:400px;
    height:400px;
    background-color: orange;

  }
  strong{
    /* 浮动规则四：浮动元素不能与行内级内容层叠，行内几内容将会被浮动元素推出 */
    float:left;
    
  }
  
  </style>
  
</head>
<body>
  <div class="box">
    <span>我是span元素</span>
    <strong>我是strong元素</strong>
    <i>我也是i元素</i>
    <div>我也是普通的内容</div>
  </div>
</body>
</html>